They are HD 3.5 1.44MB floppies... I tape over the hole and try "Format A: /F:720" but I get "Invalid Media or Track 0 Bad. Disk Unusable" ... There's nothing wrong with the disks because I can format and use them as 1.44s just fine (without the tape) and if I put them in an XT with the tape and just use Format it automatically formats them as 360K! THIS I don't understand -- are there actually 3.5" floppy drivers that are 360K and not 720? What would be the point? That system already has a 5.25" drive so I can't imagine that would be the case.
Gembird External Usb 3.5 Floppy Disk Drive Driver
As for the XT, this is just a "bug" because all XT bioses can only use 360k 5"1/4 floppy disks. There are several methods to remove that limitation such as using a controller that has a rom, or just through software. DOS 3.3 and up have a function for this, but I can't recall which. Or just use 2M-XBIOS.COM that allows you to do the exact same ?
If it's a newer USB floppy drive, you're out of luck, those don't support 720k. I do have old Teac, NEC and Iomega USB floppy drives and they have no problems with 720k, but new noname drives (like ConnectIT) simply won't do.
Not a USB floppy drive -- I forgot the brand but it came with the old Dell XPS. It is strange that it can't format the disk anything while taped, but if I format the taped disk in the XT (which is actually a Tandy 1000 running DOS 5) then the Dell will recognize that now 360K formatted disk..
If you cover the hd detection hole, the disk drive will use a lower write current, since that is different between dd and hd. However, that lower write current is too weak for the coating of hd disks. It's not supposed to work.
Tandy SX (MS DOS 5.0) -- Can read 720K disks that I've formatted on the Dell, but whether taped or untaped /F:720 always yields "Parameters not compatible". Format without any parameters will format any floppy to 360K - tape or no tape.
I don't know if this is a useful piece of information, but I got an XT clone with both 360KB (5.25") and 720KB (3.5") drives installed.Originally, I thought the 3.5" drive it came with was an early 360KB model,since without loading any additional floppy driver, both drives were stuck to 360KB of capacity.
If you say so ... But I've got 3 XT boards (2 IBM from 1986 and a more modern one from 1988) and none of them do support 3.5" floppy disk drive. A friend of mine also have an XT with the same problem and I've seen many like that on the internet 2ff7e9595c
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